This application claims the priority of German Patent Document DE 101 02 646.3, filed Jan. 20, 2001, the disclosure of which is expressly incorporated by reference herein.
The invention relates to an airbag system for motor vehicles. The airbag system has an airbag and a deployment arrangement, which fills the airbag with gas when an event occurs that can be interpreted as an impact against an obstacle. The deployment arrangement includes two independently-deployable chambers, each of which is capable of filling the airbag. The first chamber may fill the airbag more fully than the second chamber. After the first chamber has been deployed, the second chamber is deployed with a time delay.
Airbag systems have become standard equipment for protecting motor-vehicle passengers in accidents. An acceleration sensor provided on the vehicle frame usually detects whether an abrupt deceleration of the vehicle is to be interpreted as an impact against an obstacle. In such a case, a folded-up airbag is filled with gas in fractions of a second through the deployment or ignition of a propellant charge in order to catch the passenger's body and thus protect it against sustained injuries.
Airbag systems of this type have performed well in practice. Vehicles of the upper-middle class, however, are already being provided with dual-stage airbag systems, in which the deployment arrangement comprises two chambers that contain an unequal distribution of the respective propellant charge. Conventionally, the propellant chamber with the larger quantity of propellant charge (e.g., 70%) is deployed first. After a delay, the chamber having the correspondingly smaller quantity of propellant charge (e.g., 30%) is deployed. It is known to make the time delay variable, notably as a function of the severity of the accident or crash as detected and assessed by appropriate sensors (EP 0 950 582 A2).
It has been seen that, for particular accident situations, these conventional airbag systems cannot ensure the optimum protection of the passengers in the involved vehicle. The passenger may be subjected to significant stress, especially a passenger in the so-called OOP (out-of-position) situation, in which his position differs from that of an average or standard passenger. In the OOP situation, the passenger is typically too close to the airbag system, for example due to a braking action that has occurred prior to the crash or impact. Non-belted children seated in the passenger seat are particularly at risk. They may be located directly in the expansion space of the passenger airbag. To offer protection to those passengers in the OOP situation in the event of an impact, it has already been proposed to place less propellant charge in the first chamber than in the second chamber (DE 195 51 0980.A1, EP 0 958 974 A2). This, however, is a drawback for a passenger in the average or standard position.
In view of this, it is the object of the present invention to disclose an airbag system that functions optimally for the affected passenger in any accident situation.
The invention uses sensors to detect numerous person-specific variables, especially accident-specific variables, such as the sitting position, weight, size, the locked position of the safety belt, etc. Typical accident-specific variables include the actual vehicle speed and the vehicle speed relative to a vehicle traveling in front of it, as well as the nature of the crash.
With these sensors, it is possible to implement the reversible ignition sequence of the propellant charges of the two chambers in accordance with the invention.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing.